Pull means for hot wire flashers or the like



April 1.964 J. SCHMIDINGER 3,131,274

PULL MEANS FOR HOT WIRE FLASHERS OR THE LIKE Filed Jan. 25, 1961 1 -1. {A 4a, T CI 46, i 43a 50'" 1.! .W hi-3W"- 1h. 1"" Ki HIM E I N V E N TO R Jam fic/mww m e %Mw- 4 ATTORNEYS United States Patent 3,131,274 PULL MEANS FQR HUT WIRE FLAdi-HERS (Elli THE LIKE .iuseph Schmldinger, RD. ll, Assembly Point, Lake George, FLY. Filed Jan. 25, 19 51, Ser. No. 84,854 4 Qlaims. (til. 200-122) The present invention relates to hot wire interrupters or flashers of the type wherein expansion and contraction of a pull strip controls snap action of a circuit controlling element, the element being held in one position by the pull means when the pull means is cold and snapping into another position upon expansion of the pull means with passage of current therethrough. The invention comprises an improved form of pull means for a device of the above generally described type. The Schmidinger Reissue Patent No. 24,023 and Schmidinger Patent 2,906,835 disclose hot wire snap action devices which are typical of the type of devices in which the new pull means of the invention can be advantageously employed.

An important use for devices of the above described type is for control of turn signal lamps of automobiles. Among the automobile manufacturers specifications for such devices is the requirement that speed or rate of flashing and ratio or on time to full cycle, should not change appreciably with change in ambient tern pcrature. To meet this requirement the pull strip should operate at relatively high temperature which means it should consume substantial wattage. As larnp current and car carried battery voltage are standardized, the wattage in the pull means can be increased only by increase in resistance. However, if the pull means is reduced in section to increase the resistance thereof and thereby increase the consumed wattage its tensile strength is correspondingly reduced. Also a pull ribbon or wire of small cross section provides relatively small areas for attachment to the movable member and for attachment at its center either to a support means for the device or to an electrical contact for operation of the device.

In accordance with the present invention a pull ribbon is provided which is so shaped that it has a resistance high enough to provide the desired wattage, has sufficient surface area for rapid cooling when the circuit thereto is open and has sufficient surface area for ease of attachment, as by welding, to the circuit controlling element and to a support or contact. The new pull ribbon may be readily manufactured and may take various forms. In the preferred embodiment of the invention the new pull means comprises a relatively wide and thin strip or ribbon of a suitable nickel alloy having a series of elongated slots therein spaced longitudinally along the ribbon in accordance with the dimensions of a buckling member to which it is to be attached and in accordance with the element, either a fixed support or contact, which is to be attached thereto. In another embodiment of the invention a similar relatively wide and thin ribbon is cut away along each side at intervals to provide narrow sections alternating with sections of greater width.

For a better understanding of the invention and of the advantages thereof reference may be had to the accompanying drawing of which FIG. 1 is a plan view of a continuous metal strip of preferred configuration from which a plurality of pull means may be cut;

FIG. 2 is a similar view of a continuous metal strip of diiferent configuration;

FIG. 3 is a plan View of a buckling member having attached thereto a pull means corresponding to a section of the strip of FIG. 1;

3,131,274 Patented Apr. 28, 1964 W6. 4 is a diagrammatic side view of a flasher incorporating the buckling member and pull means of FIG. 3; and

FIG. 5 is a side view of another flasher provided with the pull means of the invention.

in MG. 1 there is shown a long strip 2 of a suitable nickel alloy such as nichrome which has elongated slots la and 4b of equal length therein. The slots may be readily formed in the strip 2 by a stamping operation preferably using dies shaped to provide rounded ends to each slot. The spacing between a slot 4a and the slot 4b to the left thereof, as viewed in FIG. 1 is greater than that between a slot 40 and the slot 4b on the right thereof. The spacing between the slots and the other physical dimensions of the strip are correlated to the particular element to which the pull means is to be attached as will be apparent as the description proceeds.

FIGS. 3 and 4 illustrate the flasher of Reissue Patent No. 24,023 incorporating a pull means cut from a strip such as that illustrated in FIG. 1. In FIG. 3 a buckling member 6 which has a deformation along an axis x--x tending to make it bow convexly toward the observer has a pull strip 2a overlying the deformation and welded at its ends to the buckling member adjacent the ends of the deformation therein. The pull strip 2a is a cut section of strip 2 of FIG. 1 between the dashed lines A-A, that is a section between mid points of the wider spacings between slots of the strip. The ends of the pull strip 2a are turned under the buckling member 6 and spot welded thereto under tension suflicient to bow the member oppositely to the deformation therein and about an axis y-y at right angles thereto. The part of the strip between the ends of slots in and 4b is thus positioned over the center of buckling member and provides an area for attachment to a support such as that shown at 8 in FIG. 4. The center of the buckling member on the concave side of the deformation has a contact 10 mounted thereon which, when the pull strip is cold, engages a contact 12 spring mounted on a support 14. Supports 8 and 14 extend through a molded base 16 to form prong terminals 1t and 20 of the flasher.

When a lamp load to be flashed is connected in series with a suitable source of energy across terminals 18 and 20, the current flowing through the pull strip rapidly heats the strip and causes it to be expanded and release the tension therein. The buckling member then snaps toward the position to which it is biased by the deformation therein, separating the contacts. The consequent cooling of the pull strip with resultant increase in tension therein snaps the buckling member back into circuit closing position.

With the above described pull ribbon relatively high electrical resistance is provided because of the narrow portions of the ribbon along the side edges of the slots. This increase in resistance and therefore of wattage consumed by the ribbon insures rapid and stable operation of the flasher that is substantially independent of ambient temperature. The shape of the pull means does not interfere with ample area for welding of the ends of the ribbon to the buckling member nor with ample area to which the support can be attached.

Specific dimensions of a strip like that of FIG. 1 that have been found suitable for use in a flasher such as that of FIG. 4 are now given by way of example only.

Inch Strip width .080 Strip thickness .004 Slot length .260 Shorter spacing between slots .200 Longer spacing between slots .320

In FIG. 2 an alternative form of pull strip is disclosed 3 as comprising a ribbon 22 having cut away portions 24 on either side thereof leaving intermediate the cut away portions relatively square areas 26. In the particular embodiment of the invention illustrated in FIG. 2 the lengths of each cut away portion are equal thus equally spacing the square sections 26. The particular spacing will depend upon the dimensions of the buckling men her to which sections of the strip are to be attached. If a section of the pull strip 22 of FIG. 2 is to be employed in a device such as that of FIGS. 3 and 4 the spacing between square areas 26 would be such as to bring one such square area over the center of the buckling member and adjacent square areas at points of attachment to the buckling member. The strip of FIG. 2 like that of FIG. 1 insures increase in electrical resistance as compared to a strip of uniform width and thickness.

In FIG. 5 is shown an alternative form of flasher utilizing a pull strip embodying the invention. In this embodiment of the invention a rectangular buckling member 28 is provided with a pull ribbon 22a of the configuration of the strip of FIG. 2. For this purpose the spacing of the areas 26 is such that when the pull strip 22 is cut through alternate areas 2d the intermediate section 25 will overlie the center of the buckling member 28 and the cut sections 26 will be of sufiicient area to be Welded to the corners, or adjacent the corners, of the buckling member. In the particular flasher of FIG. 5 the buckling member 28 is deformed about a longitudinal axis x-x so as to be convex toward the observer and a contact 39 is mounted on the enlarged area 26 at the central portion of the pull strip. A fixed contact, not shown in FIG. 5, is provided for engagement with contact 30 when the pull ribbon is cold. The buckling member 28 is supported by a fixed support 32 that is welded to the buckling member adjacent the lower edge thereof and preferably slightly nearer the corner of the buckling member to which the pull strip is not attached. The flasher of FIG. 5 operates substantially like that of FIG. 4.

Although the specific pull means 22a of the flasher shown in FIG. 5 is that of the strip of FIG. 2, obviously the pull means could be a section from the strip of FIG. 1.

The invention has now been described with reference to two specific shapes of pull ribbon and with reference to two particular flashers. However, the invention in its broadest aspects is not concerned with the particular structure of flasher with which the pull strip is employed. For example, a sprung vane type of flasher such as is shown in FIG. 6 of Schmidinger Patent 2,906,835 could employ the pull strip of the invention as could also the snap plate type of flasher disclosed in FIG. 8 of the said patent or the magnetic flasher disclosed in FIG. 1 thereof.

From the foregoing description it will be apparent that the invention provides a novel pull strip of relatively ligh resistance, which may be readily manufactured from flat ribbon material and which has adequate surface area for mounting in a hot wire type of flasher. Obviously various configurations of the new pull strip could be employed other than those specifically illustrated in FIGS. 1 and 2 and various dimensions and spacing of formed parts could be employed depending upon the particular application.

The following is claimed:

1. A flasher for directional signals comprising a buckling member which snaps from one circuit controlling position to another circuit controlling position in response to the expansion and contraction of a pull means, and an improved pull means which comprises a flexible ribbon of current expansible metal having spaced lengths of unequal width and uniform thickness, the lengths of lesser widths insuring rapid heating of pull means in one circuit controlling position of the buckling member and the lengths of greater width insuring rapid cooling of the pull means in the other circuit controlling position of the buckling member, said improved pull means being secured under tension to the buckling member at spaced areas of greater ribbon width.

2. The flasher according to claim 1 wherein said improved pull means includes a length of wider width intermediate the areas of attachment to the buckling member to serve for attachment of current carrying means.

3. The flasher according to claim 1 wherein the ribbon is provided with a plurality of longitudinal slots along its longitudinal axis the lengths of the slots determining the spaced lengths of lesser width.

4. The flasher according to claim 1 wherein the ribbon has oppositely disposed open sided slots along the side edges thereof, the lengths of the slots determining the spaced lengths of lesser width.

References Cited in the file of this patent UNITED STATES PATENTS 2,028,720 LaMar Jan. 21, 1936 2,615,106 Schmidinger Oct. 21, 1952 2,673,444 Clapp Mar. 30, 1954 2,839,634 Clark June 17, 1958 2,879,355 Welsh Mar. 24, 1959 

1. A FLASHER FOR DIRECTIONAL SIGNALS COMPRISING A BUCKLING MEMBER WHICH SNAPS FROM ONE CIRCUIT CONTROLLING POSITION TO ANOTHER CIRCUIT CONTROLLING POSITION IN RESPONSE TO THE EXPANSION AND CONTRACTION OF A PULL MEANS, AND AN IMPROVED PULL MEANS WHICH COMPRISES A FLEXIBLE RIBBON OF CURRENT EXPANSIBLE METAL HAVING SPACED LENGTHS OF UNEQUAL WIDTH AND UNIFORM THICKNESS, THE LENGTHS OF LESSER WIDTHS INSURING RAPID HEATING OF PULL MEANS IN ONE CIRCUIT CONTROLLING POSITION OF THE BUCKLING MEMBER AND THE LENGTHS OF GREATER WIDTH INSURING RAPID COOLING OF THE PULL MEANS IN THE OTHER CIRCUIT CONTROLLING POSITION OF THE BUCKLING MEMBER, SAID IMPROVED PULL MEANS BEING SECURED UNDER TENSION TO THE BUCKLING MEMBER AT SPACED AREAS OF GREATER RIBBON WIDTH. 